Make sure you add the Itextsharp dll to the global assembly cache (GAC) on your server.
For 2010 the GAC is found under
C:\Windows\assembly
For 2013
C:\windows\microsoft.net\assembly\GAC_MSIL
Make sure you add the Itextsharp dll to the global assembly cache (GAC) on your server.
For 2010 the GAC is found under
C:\Windows\assembly
For 2013
C:\windows\microsoft.net\assembly\GAC_MSIL